Pass a char *, pointing to a zero terminated string holding the list of ciphers
to use for the connection to the HTTPS proxy. The list must be syntactically
correct, it consists of one or more cipher strings separated by colons. Commas
or spaces are also acceptable separators but colons are normally used, !, -
and + can be used as operators.

For OpenSSL and GnuTLS valid examples of cipher lists include
'RC4-SHA', ´SHA1+DES´, 'TLSv1' and 'DEFAULT'. The default list
is normally set when you compile OpenSSL.

For NSS, valid examples of cipher lists include 'rsa_rc4_128_md5',
´rsa_aes_128_sha´, etc. With NSS you don't add/remove ciphers.
If one uses this option then all known ciphers are disabled and only those
passed in are enabled.